1. Field of the Invention
The present invention relates to a system enabling data communications between an electronic control apparatus and a test apparatus for testing the electronic control apparatus. More specifically, the invention relates to a communications system connected to enable data sending and receiving between an electronic control apparatus comprising a serial asynchronous communications function or mode for transmitting data and a test apparatus for checking the operation of said electronic control apparatus wherein the communications mode of the test apparatus differs from that of the electronic control apparatus.
One application for the invention is to enable data communications between a test apparatus and an automotive electronic control apparatus used for antilock brake control, engine control, or other automotive applications.
2. Description of the Prior Art
One type of common electronic control apparatus today is the electronic control unit used in automobiles to control the antilock brake control system.
In such an application, the electronic control apparatus calculates the vehicle speed, acceleration/deceleration of each wheel, and other parameters based on the input signals output from wheel speed sensors and other devices. When wheel skidding is detected from the minimum detected wheel speed and from the relationship between vehicle speed and wheel speed, the electronic control apparatus outputs control signals to the solenoids and motors used to drive the reflux pump and other components to alleviate skidding. These electronic control apparatuses also typically store a troubleshooting code that identifies trouble spots when a problem develops in the wheel speed sensors or other components.
These electronic control systems are typically self-regulating with a test apparatus provided to check whether the control signals are output to the motor and solenoids, and to read the troubleshooting codes to confirm the identified problem area. In such systems, the electronic control apparatus and test apparatus are linked via a communications bus, and data is sent and received between the components using serial communications protocols.
Two serial communications formats are commonly used: full duplex in which two signal buses are used discretely for sending and receiving, and half duplex in which one signal bus is used for both sending and receiving. As a result, if the electronic control apparatus and the test apparatus do not use the same communications format, it is not possible for data to be sent between the two devices.
This is a particular problem in mobile electronic control apparatuses because the communications formats of the electronic control apparatus are often different in different models and vehicle makes. This makes it necessary to have test apparatuses compatible with the different communications formats of the electronic control units, resulting in increased cost and inconvenience.